Social media allows people to connect and share information online through sites like Facebook and Twitter. Facebook allows sharing of photos, videos, and links with friends, while Twitter limits posts to 140 characters but makes content searchable. Other popular sites mentioned include Yelp for reviews, Foursquare for checking in, and WordPress for blogging. The document provides statistics on Twitter usage and tips for setting up an account, using hashtags and retweets, and ideas for social media content and engagement.